The present invention pertains to a system for diagnosis of brainstem disorders, such as schizophrenia, and particularly to a method of using said system in respect of diagnosis of brainstem disorders, such as schizophrenia.
Disorders of the nervous system are a growing concern. One area of nervous disorders are brainstem disorders. One such disorder is schizophrenia—a hereditary disease—which is a disruption in the nerve transmission within and between all systems in the nervous system which handle the electrical representation of the tactile sense, vision, hearing, thinking and motor functions. The origin of the disease is hitherto unknown.
Today there are no established, objective measures for determining schizophrenia. Clinical diagnostics, which means clinical observation and evaluation of the patient's symptoms is most commonly used to diagnose schizophrenia.
Psychological tests are being used, but these measure general functions which are not specific for schizophrenia. A vast number of visual and psychological tests of perception are described in the literature but these are solely of scientific interest and are not being used clinically. Furthermore, no tests available today have sufficiently predictive abilities regarding schizophrenia.
By using several psychological functioning tests a prediction for schizophrenia at below 70% can be achieved. This means that in 70% of the cases the schizophrenic-typical test results leads to a diagnosis later. Thus the specificity is still rather uncertain.
Diagnostic methods at hand today are very time consuming. Regarding forensic psychiatry a process of at least 30 working days and an investigation team comprising at least six professionals is needed to set a more reliable diagnosis. Admissions with months of observations and investigations are common procedure and sometimes the diagnosis can be established only after years of follow-ups in the non-institutional care. In conclusion, today diagnoses are established by means of traditional psychiatric observation, a time consuming process which leads to a much more severe disease. Thus, with today's diagnostic methods it is most frequently too late for efficient therapeutic treatment.
Organic alterations, today measurable by means of neuro-imaging techniques, reflect late physiological effects of the disease. The psychological cognitive tests that are being used in diagnostics measure frontal lobe dysfunction and word-tests indicate temporal lobe dysfunction, which both are late processes too. Psychological tests are more aimed at diagnosing dementia than schizophrenia.
Electrophysiology can give some information for example by means of P300. P300 is a positive wave in the electroencephalogram (EEG) which correlates with a large number of repeated stimuli presented through the hearing or visual modalities. It is claimed to be an expression of the nervous system's regulation of attentiveness. However, the variation within this measure obtained is far too large to obtain diagnostic reliability for schizophrenia and the need of more precise instruments for diagnostic purposes is acute. To obtain an objective measure on the early schizophrenia, specific stimulation and ascertained correlation between the results and other diagnostic measures of the disease are needed. The majority of patents regarding schizophrenia are based on biochemical and genetic models and practically oriented clinical test is not disclosed.
In patent WO-AI-03026500 a psycho-physiological test for diagnosis of schizophrenia is disclosed. The document describes a device and method for measurement of binochular rivalry. This psycho-physiological test demands the subject's active participation as reflected by decision-making and pushing a button, and thus it cannot be regarded being truly physiologically objective. This issue is of uttermost importance, since it might interfere with the perceptual process.
The state of the art refers to the usage of simple sound stimulation, such as click trains, with identical click or pulse trains with isolated differing pulses, whereby the brain reaction to difference is recorded, to obtain electrophysiological brain (cortex) reading in respect of schizophrenia diagnosis. This is called MMN (MisMatch Negativity). The time span used in MMN is in the interval 80 to 300 ms.
U.S. Pat. No. 5,954,667 discloses a device for derivation of acoustically evoked brain potentials. The triggering mentioned in U.S. Pat. No. 5,954,667 concerns the generation of a sequence of clicks when the device is activated by a finger operable switching action. Therefore, the measurement of brain activity occurs during a longer time and not simultaneously as the sound stimulation. Every click sound in U.S. Pat. No. 5,954,667 does not release a new reading of brain activity. Therefore, the device according to U.S. Pat. No. 5,954,667 is not capable of detecting, and diagnosing, brain disorders, such as schizophrenia, but only capable of controlling the hearing in subjects, such as a child, incapable of actively responding to sound stimuli.
Other documents disclosing the state of the art are the two articles; “Novelty-elicited mismatch negativity in patients with schizophrenia on admission and discharge”, Journal of Psychiatry & Neuroscience, vol 26, nr 3, 2001, pages 235 to 246; and Nisad, Schizophrenia Research, Research News, March 2003.
Hence, an improved system, and a method thereof, for diagnosis of brainstem disorders, such as schizophrenia, would be advantageous and in particular a system allowing for a testing procedure that does not rely on any cognitive effort from the subject would be advantageous. Also, specificity and reliability of the diagnosis should be more advantageous.